Optical filter, and camera module and electronic device comprising the same

ABSTRACT

Disclosed are an optical filter including a near infrared absorption layer on a polymer film. The polymer film has a* of about −5.0 to about +5.0 and b* of about −5.0 to about +5.0 in a color coordinate expressed by a CIE Lab color space. The near infrared absorption layer may be configured to transmit light in a visible region and to selectively absorb at least one part of light in a near infrared region. The near infrared absorption layer includes a first near infrared absorption material including a copper phosphate ester compound and a second near infrared absorption material including at least two different organic dyes. The second near infrared absorption material has a maximum absorption wavelength (λ max ) in a wavelength region of about 650 nm to about 1200 nm. An electronic device may include the optical filter.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2017-0144897 filed in the Korean IntellectualProperty Office on Nov. 1, 2017, the entire contents of which areincorporated herein by reference.

BACKGROUND 1. Field

An optical filter and a camera module and an electronic device includingthe same are disclosed.

2. Description of the Related Art

Recently, an electronic device including an image sensor that stores animage as an electrical signal, such as a cell phone, a digital camera, acamcorder and a camera, has been widely used.

This electronic device may include an optical filter having nearinfrared ray absorption capability in order to reduce or preventgeneration of an optical distortion by light in the other regions than avisible region.

This optical filter in general is mounted in front of an image sensor ofa camera module and thus plays a role of effectively absorbing anincident near infrared ray and resolving the optical distortionphenomenon.

Recently, several attempts to make the optical filter into a thin filmcorresponding to a demand on down-sizing, higher integration, and thelike of an electronic device and particularly, a couple of attempts toreplace a glass substrate for a conventional optical filter with aplastic substrate have been made.

The above plastic substrate may a contribute little to thinning theoptical filter but cause a flare phenomenon where a border around asubject is seen (a wifi-type flare phenomenon), light around the subjectis spread or glimmered (a petal-type flare phenomenon), or the like,when the subject with high luminance is observed or imaged.

This flare phenomenon is an optical distortion caused according as animage sensor in an electronic device senses light in a visible raywavelength region along with an infrared ray or near infrared raywavelength region.

SUMMARY

Some example embodiments provide an optical filter capable of reducingand/or minimizing an optical distortion phenomenon of an image sensorand being made into a thin film and in addition, a camera module and anelectronic device including the optical film and capable of reducingand/or minimizing an optical distortion of an image.

According to some example embodiments, an optical filter includes apolymer film having a* of about −5.0 to about +5.0 and b* of about −5.0to about +5.0 in a color coordinate expressed by a CIE Lab color space;and a near infrared absorption layer on the polymer film. The nearinfrared absorption layer is configured to transmit light in a visibleregion and to selectively absorb at least one part of light in a nearinfrared region. The near infrared absorption layer includes a firstnear infrared absorption material and a second near infrared absorptionmaterial. The first near infrared absorption material includes a copperphosphate ester compound. The second near infrared absorption materialincludes at least two different organic dyes. The second near infraredabsorption material has a maximum absorption wavelength (λmax) in awavelength region of about 650 nm to about 1200 nm.

In some example embodiments, the optical filter may have an averagelight transmittance of less than or equal to about 25% in a wavelengthregion of about 700 nm to about 1200 nm.

In some example embodiments, the optical filter may have an averagelight transmittance of less than or equal to about 5% in a wavelengthregion of about 700 nm to about 740 nm and the optical filter may havean average light transmittance of less than or equal to about 25% in awavelength region of about 1000 nm to about 1200 nm.

In some example embodiments, the optical filter may have an averagelight transmittance of greater than or equal to about 80% in awavelength region of about 430 nm to about 565 nm.

In some example embodiments, the second near infrared absorptionmaterial may include a binder. The at least two organic dyes of thesecond near infrared absorption material may include an organic dyerepresented by Chemical Formula 1, and at least one of an organic dyerepresented by Chemical Formula 2 or an organic dye represented byChemical Formula 3.

In Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3, R¹ toR²⁶ may independently be a hydrogen atom, a substituted or unsubstitutedC1 to C20 alkyl group, or a substituted or unsubstituted C6 to C20 arylgroup; X may be one of PF₆ ⁻, BF₄ ⁻, ClO₄ ⁻, I⁻, or a borate-basedanion; and n may be an integer ranging from 1 to 10.

In some example embodiments, the organic dye represented by ChemicalFormula 1 may include one or more structures represented by at least oneof Chemical Formula 1a, Chemical Formula 1b, Chemical Formula 1c,Chemical Formula 1d, or Chemical Formula 1e.

In some example embodiments, the organic dye represented by ChemicalFormula 2 may include one or more structures represented by at least oneof Chemical Formula 2a, Chemical Formula 2c, or Chemical Formula 2c.

In some example embodiments, the organic dye represented by ChemicalFormula 1 may have a maximum absorption wavelength (λ_(max)) in awavelength region of about 700 nm to about 760 nm. The organic dyerepresented by Chemical Formula 2 may have a maximum absorptionwavelength (λ_(max)) in a wavelength region of about 1050 nm to about1100 nm. The organic dye represented by Chemical Formula 3 may have amaximum absorption wavelength (λ_(max)) in a wavelength region of about680 nm to about 720 nm.

In some example embodiments, the binder may include an acrylic binder,an epoxy binder, or a combination thereof.

In some example embodiments, the organic dye represented by ChemicalFormula 1 may have an absorbance at a maximum absorption wavelength(λ_(max)) that is at least about 30 times as high as an absorbance ofthe organic dye represented by Chemical Formula 1 at a wavelength ofabout 550 nm. The organic dye represented by Chemical Formula 2 may havean absorbance at a maximum absorption wavelength (λ_(max)) that is atleast about 15 times as high as an absorbance of the organic dyerepresented by Chemical Formula 2 at a wavelength of about 550 nm.

In some example embodiments, the copper phosphate ester compound may berepresented by Chemical Formula 4.

In Chemical Formula 4, R41 and R42 are independently one of asubstituted or unsubstituted C1 to C20 alkyl group, a substituted orunsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2to C20 alkynyl group, or a substituted or unsubstituted C6 to C20 arylgroup; n1 is an integer of 0 or 1; and n2 is an integer of 1 or 2.

In some example embodiments, the copper phosphate ester compoundrepresented by Chemical Formula 4 may include one or more structuresrepresented by at least one of Chemical Formula 4a, Chemical Formula 4b,Chemical Formula 4c, or Chemical Formula 4d.

In some example embodiments, the near infrared absorption layer mayinclude a first near infrared absorption layer and a second nearinfrared absorption layer. The first near infrared absorption layer mayconsist of the first near infrared absorption material The second nearinfrared absorption layer may consist of the second near infraredabsorption material. The first near infrared absorption layer and thesecond near infrared absorption layer may be separate layers from eachother.

In some example embodiments, the first near infrared absorption layermay be on the polymer film and the second near infrared absorption layermay be on the first near infrared absorption layer.

In some example embodiments, the optical filter may further include ananti-reflection layer on at least one of one surface of the polymer filmor one surface of the near infrared absorption layer.

In some example embodiments, the anti-reflection layer may include afirst layer and a second layer. A refractive index of the first layermay be different than a refractive index of the second layer. The firstlayer and the second layer may be alternately stacked two or more.

In some example embodiments, the anti-reflection layer may be on the onesurface of the polymer film and the one surface of the near infraredabsorption layer, respectively.

In some example embodiments, the polymer film may include one ofpolyethyleneterephthalate, polyethylenenaphthalate, triacetyl cellulose,polycarbonate, a cycloolefin polymer, poly(meth)acrylate, polyimide, ora combination thereof.

In some example embodiments, a yellow index of the polymer film measuredaccording to ASTM D1925 may be less than or equal to about 10 and a hazeof the polymer film may be less than or equal to about 10%.

In some example embodiments, the optical filter may have a thickness ofabout 25 μm to about 190 μm.

According to some example embodiments, a camera module includes a pairof lens; an image sensor; and the optical filter between the lens andthe image sensor.

According to some example embodiments, an electronic device includingthe optical filter is provided.

According to some example embodiments, an optical filter includes apolymer film having a* of about −5.0 to about +5.0 and b* of about −5.0to about +5.0 in a color coordinate expressed by a CIE Lab color space;and a near infrared absorption layer on the polymer film. The nearinfrared absorption layer includes a first near infrared absorptionlayer and a second near infrared absorption layer. The first nearinfrared absorption layer includes a copper phosphate ester compoundrepresented by Chemical Formula 4. Chemical Formula 4 may have the samestructure as described above. The second near infrared absorption layermay include a plurality of organic dyes having a maximum absorptionwavelength (λ_(max)) in a wavelength region of about 650 nm to about1200 nm.

In some example embodiments, the copper phosphate ester compoundrepresented by Chemical Formula 4 may include one or more structuresrepresented by at least one of Chemical Formula 4a, Chemical Formula 4b,Chemical Formula 4c, or Chemical Formula 4d. The plurality of organicdyes may include a first organic dye represented by Chemical Formula 1and at least one of a second organic dye presented by Chemical Formula 2or a third organic dye represented by Chemical Formula 3. The structuresof Chemical Formulas 1, 2, 3, 4a, 4b, 4c, and 4d may be the same asdescribed above.

In some example embodiments, the optical filter may further include atleast one of a binder in the second near infrared absorption layer, oran anti-reflection layer on the polymer layer.

In some example embodiments, an electronic device may include aphotoelectric device and the optical filter on the photoelectric device.

In some example embodiments, an electronic device may include asubstrate, a photo-sensing device integrated with the substrate, and theoptical filter on the photo-sensing device.

According to some example embodiments, the optical filter has a highabsorption rate about light in a near infrared ray wavelength region andthus may reduce and/or minimize an optical distortion of an image sensorand be made into a thin film.

In addition, the camera module and the electronic device includes theoptical filter and may provide an image having a reduced and/orminimized optical distortion and be easily applied to a much down-sizedcamera module and electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a stack structure of an opticalfilter according to some example embodiments,

FIGS. 2 to 5 show various examples of disposition relationships of thenear infrared absorption layer in the optical filter of FIG. 1,

FIG. 6 is a schematic view showing a stack structure of an opticalfilter including an anti-reflection layer according to some exampleembodiments,

FIGS. 7 and 8 are schematic views showing various stack structures ofthe anti-reflection layer,

FIGS. 9 to 13 show various examples of disposition relationships of ananti-reflection layer in an optical filter according to some exampleembodiments,

FIG. 14 is a schematic view showing a camera module according to someexample embodiments,

FIG. 15 is a top plan view showing an organic CMOS image sensor as anexample of an image sensor,

FIG. 16 is a cross-sectional view showing an example of the organic CMOSimage sensor of FIG. 15, and

FIG. 17 is a graph showing a light transmittance verse a wavelength ofthe optical filters according to examples and comparative examples.

DETAILED DESCRIPTION

As used herein, when specific definition is not otherwise provided,“alkyl group” refers to a C1 to C20 alkyl group and “aryl group” refersto a C6 to C20 aryl group.

As used herein, when specific definition is not otherwise provided,“substituted” refers to replacement of at least one hydrogen by ahalogen atom (F, Cl, Br, or I), a hydroxy group, a C1 to C20 alkoxygroup, a nitro group, a cyano group, an amine group, an imino group, anazido group, an amidino group, a hydrazino group, a hydrazono group, acarbonyl group, a carbamyl group, a thiol group, an ester group, ethergroup, a carboxyl group or a salt thereof, a sulfonic acid group or asalt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkylgroup, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C20aryl group, a C3 to C20 cycloalkyl group, a C3 to C20 cycloalkenylgroup, a C3 to C20 cycloalkynyl group, a C2 to C20 heterocycloalkylgroup, a C2 to C20 heterocycloalkenyl group, a C2 to C20heterocycloalkynyl group, a C3 to C20 heteroaryl group, or a combinationthereof.

As used herein, when a definition is not otherwise provided, in chemicalformula, hydrogen is bonded at the position when a chemical bond is notdrawn where supposed to be given.

As used herein, the average light transmittance refers to an averagevalue of light transmittance measured when incident light is radiated ina vertical direction (front direction) of the optical filter. As usedherein, “maximum absorption wavelength” refers to a wavelength at whichthe absorption intensity is the maximum, and it can also be referred toas peak absorption wavelength.

Hereinafter, example embodiments will be described in detail so that aperson skilled in the art would understand the same. This disclosuremay, however, be embodied in many different forms and is not construedas limited to the example embodiments set forth herein.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

Hereinafter, an optical filter according to some example embodiments isdescribed with reference to FIGS. 1 to 13.

FIG. 1 is a schematic view showing a stack structure of an opticalfilter according to some example embodiments.

Referring to FIG. 1, an optical filter 10 according to some exampleembodiments includes a polymer film 11 and a near infrared absorptionlayer 12.

The polymer film 11 may be a transparent polymer film and have forexample an average light transmittance of greater than or equal to about80%, greater than or equal to about 85%, greater than or equal to about90%, greater than or equal to about 95%, or even very close to 100% in avisible region. Herein, the visible region may be for example awavelength region of greater than about 380 nm and less than about 700nm, for example a wavelength region of about 430 nm to about 630 nm,and/or for example a wavelength region of about 430 nm to about 565 nm.The average light transmittance is an average value of lighttransmittance measured when incident light is radiated in a verticaldirection (front direction) of the polymer film 11.

The polymer film 11 may include polyethyleneterephthalate,polyethylenenaphthalate, triacetyl cellulose, polycarbonate, acycloolefin polymer, poly(meth)acrylate, polyimide, or a combinationthereof, but is not limited thereto. The polymer film 11 may includevarious additives according to desired properties of the optical film10.

The polymer film 11 may selectively absorb at least one part of light inan ultraviolet (UV) region. Herein, the ultraviolet (UV) region may be,for example a wavelength region of less than or equal to about 380 nm.

The polymer film 11 may absorb most of light in a wavelength region ofat least about 350 nm to about 380 nm. For example, an average lighttransmittance of the optical filter 10 in a wavelength region of about350 nm to about 380 nm may be less than or equal to about 5%, less thanor equal to about 3%, less than or equal to about 1%, less than or equalto about 0.8%, or less than or equal to about 0.5%.

The polymer film 11 may have a thickness of about 25 μm to about 105 μm,but is not limited thereto.

The polymer film 11 may have a* of about −5.0 to about +5.0 and b* ofabout −5.0 to about +5.0 in a color coordinate expressed by a CIE Labcolor space. The polymer film 11 may have a* of about −3.0 to about+3.0, for example about −1.5 to about +1.5 and b* of about −3.0 to about+3.0, for example about −1.5 to about +1.5. On the other hand, a rangeof L in a color coordinate is not particularly limited.

When the polymer film 11 satisfies the range of a* and/or b* on thecolor coordinate, a color distortion phenomenon by the optical filter 10may be limited and/or minimized.

A yellow index (YI) of the polymer film 11 may be for example less thanor equal to about 15, less than or equal to about 14, less than or equalto about 13, less than or equal to about 12, less than or equal to about11, less than or equal to about 10, less than or equal to about 9, lessthan or equal to about 8, less than or equal to about 7, less than orequal to about 6, or less than or equal to about 5.

A haze of polymer film 11 may be measured according to ASTM D1003. Thehaze of the polymer film 11 may be for example less than or equal toabout 15%, less than or equal to about 14%, less than or equal to about13%, less than or equal to about 12%, less than or equal to about 11%,less than or equal to about 10%, less than or equal to about 9%, lessthan or equal to about 8%, less than or equal to about 7%, less than orequal to about 6%, or less than or equal to about 5%.

When the polymer film 11 satisfies the yellow index and/or haze ranges,absorption, scattering, reflection, and the like of light in a visibleregion by the polymer film 11 may be limited and/or minimized, andaccordingly, the optical filter 10 may provide an image with a limitedand/or minimal color distortion.

The near infrared absorption layer 12 is configured to transmit light ina visible region and to selectively absorb at least one part of light ina near infrared region. Herein, the visible region may be for example awavelength region of greater than about 380 nm and less than about 700nm, for example about 430 nm to about 630 nm, for example about 430 nmto about 565 nm and the near infrared region may be for example awavelength region of about 700 nm to 1200 nm.

The near infrared absorption layer 12 may include a first near infraredabsorption material and a second near infrared absorption material.

The first near infrared absorption material may include a copperphosphate ester compound. The first near infrared absorption materialmay be obtained by coating and drying a composition comprising a solublecopper phosphate ester compound including acrylate group.

The copper phosphate ester compound may have vast absorption capabilityabout light in a near infrared ray wavelength region and even absorband/or reflect light in a mid-infrared region and a far-infrared raywavelength region. The copper phosphate ester compound may for exampleabsorb and/or reflect light in a wavelength region ranging from about700 nm to about 3 μm.

The copper phosphate ester compound may represented by Chemical Formula4.

In Chemical Formula 4, R⁴¹ and R⁴² are independently one of asubstituted or unsubstituted C1 to C20 alkyl group, a substituted orunsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2to C20 alkynyl group, and a substituted or unsubstituted C6 to C20 arylgroup; n₁ is an integer of 0 or 1; and n₂ is an integer of 1 or 2.

The copper phosphate ester compound represented by Chemical Formula 4may include at least one structure represented by Chemical Formula 4a toChemical Formula 4d.

In general, when UV is radiated into an optical filter, the UV may havean influence on the optical filter, a color filter, and the like andthus cause a color distortion phenomenon. Accordingly, the UV may beblocked in a method of forming a UV reflection layer on the opticalfilter and including a UV absorber (e.g., a copper compound), an organicdye (e.g., a yellow organic dye), and the like in the optical filter.

A copper phosphate salt, one copper compound, has vast absorptioncapability for light in a near infrared ray wavelength region but verylow UV absorption intensity. However, a copper phosphate saltcomposition needs to be used in an excessive amount to form a nearinfrared absorption layer. In this way, when the copper phosphate saltcomposition is used in an excessive amount to prepare a highconcentration copper phosphate ester compound solution, the copperphosphate salt composition in an excessive amount increases viscosity ofthe high concentration copper phosphate ester compound solution and thushinders the near infrared absorption layer from being formed to be thin.In other words, when the excessive amount-copper phosphate estercompound solution alone is used to form the near infrared absorptionlayer, the optical filter may not be formed into a thin film.

On the contrary, the near infrared absorption layer 12 of the opticalfilter 10 according to some example embodiments includes a second nearinfrared absorption material comprising an organic dye as well as theaforementioned first near infrared absorption material. The second nearinfrared absorption material may show excellent UV absorption intensityin a relatively small amount relative to that of the copper phosphateester compound. Accordingly, when the second near infrared absorptionmaterial is used along with the first near infrared absorption material,an optical filter having excellent UV absorption intensity and excellentnear infrared ray absorption capability in a vast region andsimultaneously formed into a thin film may be provided.

The second near infrared absorption material includes an organic dye.The second near infrared absorption material may have a maximumabsorption wavelength (λmax) within a wavelength range including a nearinfrared region and/or a part of a red region near to the near infraredregion.

The second near infrared absorption material may have a maximumabsorption wavelength (λmax) in a near infrared region including a partof a red region, for example about 650 nm to about 1200 nm, about 660 nmto about 1200 nm, about 670 nm to about 1200 nm, about 680 nm to about1200 nm, or about 690 nm to about 1200 nm. However, inventive conceptsare not limited thereto, the second near infrared absorption materialmay have a maximum absorption wavelength (λmax) in a near infraredregion almost no absorption and or not at all including the red region,for example, in a region ranging from about 700 nm to about 1200 nm, butalmost no absorption or not at all in the red region, depending on akind of the organic dye, a kind of the polymer film 11, and the like.

The second near infrared absorption material includes a binder and anorganic dye represented by Chemical Formula 1, and may further includeat least one of an organic dye represented by Chemical Formula 2 and anorganic dye represented by Chemical Formula 3.

In Chemical Formula 1 to Chemical Formula 3, R¹ to R²⁶ are independentlya hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group,or a substituted or unsubstituted C6 to C20 aryl group; X is one of PF₆⁻, BF₄ ⁻, ClO₄ ⁻, I⁻, or a borate-based anion, and n is an integerranging from 1 to 10.

The binder may be, for example an organic binder, an inorganic binder,an organic/inorganic binder, or a combination thereof, and may be mixedwith the dyes represented by Chemical Formula 1 to Chemical Formula 3 ormay disperse the dyes represented by Chemical Formula 1 to ChemicalFormula 3. The binder is not particularly limited as long as it attachesthe dyes represented by Chemical Formula 1 to Chemical Formula 3 to thepolymer film 11 well.

The binder may include an acrylic binder, an epoxy binder, or acombination thereof. In some example embodiments, the binder may be anacrylic binder. For example, the acrylic binder may be a curable binder,for example a thermally curable binder, a photo-curable binder, or acombination thereof.

The binder may be for example methyl cellulose, ethyl cellulose,hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC), axanthan gum, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP),carboxyl methyl cellulose, hydroxyethyl cellulose, or a combinationthereof, but is not limited thereto.

The organic dye represented by Chemical Formula 1 may have a maximumabsorption wavelength (λmax) in a wavelength region of about 700 nm toabout 760 nm, the organic dye represented by Chemical Formula 2 may havea maximum absorption wavelength (λmax) in a wavelength region of about1050 nm to about 1100 nm, and the organic dye represented by ChemicalFormula 3 may have a maximum absorption wavelength (λmax) in awavelength region ranging from about 680 nm to about 720 nm. When atleast two organic dyes having a maximum absorption wavelength (λmax) ina different wavelength region are used, near infrared ray absorptioncapability about a wide near infrared ray wavelength region may besecured.

The organic dye represented by Chemical Formula 1 may have greater thanor equal to about 30 times, for example, greater than or equal to about40 times, for example, greater than or equal to about 50 times, forexample, greater than or equal to about 60 times, for example, greaterthan or equal to about 70 times, and even greater than or equal to about80 times higher absorbance at a maximum absorption wavelength (λ_(max))than absorbance at a wavelength of about 550 nm.

The organic dye represented by Chemical Formula 2 may have greater thanor equal to about 15 times, for example, greater than or equal to about20 times, for example, greater than or equal to about 25 times, forexample, greater than or equal to about 30 times, for example, greaterthan or equal to about 40 times, and for example, greater than or equalto about 50 times higher absorbance at a maximum absorption wavelength(λmax) than absorbance at a wavelength of about 550 nm.

In this way, since the organic dye represented by Chemical Formula 1satisfies at least greater than or equal to about 30 times higherabsorbance at a maximum absorption wavelength (λmax) than absorbance ata wavelength of about 550 nm, and the organic dye represented byChemical Formula 2 also satisfies at least greater than or equal toabout 15 times higher absorbance at a maximum absorption wavelength(λmax) than absorbance at a wavelength of about 550 nm, the opticalfilter 10 may show high light transmittance in a visible region andsimultaneously, very low light transmittance in a near infrared region.

When the organic dye has less than about 15 times higher absorbance at amaximum absorption wavelength (λmax) than absorbance at a wavelength ofabout 550 nm, the organic dye deteriorates light transmittance in avisible region and lacks of the above property and thus may not be usedfor a near infrared absorption layer of the optical filter 10 accordingto some example embodiments.

In some example embodiments, the second near infrared absorptionmaterial includes at least two different kind of organic dyes andparticularly, may further include the organic dye represented byChemical Formula 2 and/or the organic dye represented by ChemicalFormula 3 in addition to the organic dye represented by Chemical Formula1.

When at least two different kind of organic dyes are mixed, the secondnear infrared absorption material may have near infrared ray absorptioncapability about light in different wavelength regions simultaneously,and thus the near infrared absorption layer 12 may have the nearinfrared ray absorption capability in a wider near infrared raywavelength region.

In other words, when the organic dye represented by Chemical Formula 1is used alone, light transmittance in a particular wavelength region outof the near infrared region may be set very low, but light transmittancein the other wavelength regions (e.g., 1100 nm to 1200 nm) may not beadjusted. However, when the organic dye represented by Chemical Formula2 and/or Chemical Formula 3 is further added to the organic dyerepresented by Chemical Formula 1, these organic dyes may be used in asmaller amount than that of the organic dye represented by ChemicalFormula 1 alone but lower light transmittance in a near infrared regionto be less than or equal to about 25%, less than or equal to about 20%,less than or equal to about 15%, less than or equal to about 10%, evenless than or equal to about 5%, or less than or equal to about 4%compared with the organic dye represented by Chemical Formula 1 withoutdeteriorating light transmittance in a visible region and accordingly,be appropriately used for the near infrared absorption layer 12 of theoptical filter 10.

The organic dye represented by Chemical Formula 1 may include at leastone selected from Chemical Formula 1a to Chemical Formula 1e.

The organic dye represented by Chemical Formula 2 may include at leastone selected from Chemical Formula 2a to Chemical Formula 2c.

The second near infrared absorption material may further include anorganic dye having a different structure from the organic dyesrepresented by Chemical Formula 1 to Chemical Formula 3.

The organic dye having a different structure from the organic dyesrepresented by Chemical Formula 1 to Chemical Formula 3 may be forexample a polymethine compound, a phthalocyanine compound, a merocyaninecompound, naphthalocyanine, an immonium compound, a triarylmethanecompound, a dipyrromethene compound, an anthraquinone compound,naphthoquinone, a diquinone compound, a rylene compound, a perylenecompound, a squaraine compound, a pyrylium compound, a thiopyryliumcompound, a diketopyrrolopyrrole compound, a dithiolene metal complexcompound, a derivative thereof, or a combination thereof, but is notlimited thereto.

In general, an organic dye has very excellent UV absorption intensity asdescribed above but a relatively narrow UV absorption region comparedwith copper phosphate salt and thus a limit in absorbing light in a UVregion (the organic dye alone is usefully used as a medically labelingmaterial for diagnosing a cancer, a coloring material of clothes, andthe like by using its characteristics of revealing a color but having asmall UV absorption region).

In addition, the organic dye has excellent near infrared ray absorptionintensity but a relatively narrow near infrared ray absorption regioncompared with copper phosphate salt and thus may not be used whenabsorption capability about a wide near infrared ray wavelength regionis needed.

However, the near infrared absorption layer 12 of the optical filter 10according to some example embodiments uses the first near infraredabsorption material including the copper phosphate ester compound andthe second near infrared absorption material together. In addition, thesecond near infrared absorption material uses at least two differentorganic dyes, specifically, at least one of the organic dyes representedby Chemical Formulae 2 and 3 and the organic dye represented by ChemicalFormula 1 along with a binder.

Accordingly, when the first and second near infrared absorptionmaterials are used together, a problem of the conventional organic dyehaving a narrow UV and near infrared ray absorption regions may besolved.

On the other hand, the first near infrared absorption material and thesecond near infrared absorption material are disposed on the polymerfilm 11 and herein, united and formed as one layer, as shown in FIG. 1.However, inventive concepts are not necessarily limited thereto, but thefirst and second near infrared absorption materials may respectivelyform each own layer with a consideration to compatibility and the likebetween the first and second near infrared absorption materials and beall disposed on both sides of the polymer film 11.

FIGS. 2 to 4 show various examples that the near infrared absorptionlayer in the optical filter of FIG. 1 includes the first and second nearinfrared absorption layers.

The near infrared absorption layer 12 may include a first near infraredabsorption layer 12 a formed of a first near infrared absorptionmaterial and a second near infrared absorption layer 12 b formed of asecond near infrared absorption material. The first and second nearinfrared absorption layers 12 a and 12 b are respectively formed asseparate layers.

Referring to FIG. 2, the optical filter 10 a may have a dispositionstructure that the first and second near infrared absorption layers 12 aand 12 b are disposed in order on the polymer film 11.

However, as shown in FIG. 3, the optical filter 10 b may have adisposition structure that the second near infrared absorption layer 12b and the first near infrared absorption layer 12 a are disposed inorder on the polymer film 11.

In addition, as shown in an optical filter 10 c according to FIG. 4, thefirst and second near infrared absorption layers 12 a and 12 b are atleast twice alternately disposed on the polymer film 11. On the otherhand, FIG. 4 shows that the near infrared absorption layer 12 isdisposed by disposing the first and second near infrared absorptionlayers 12 a and 12 b in order on the polymer film 11, but the second andfirst near infrared absorption layers 12 b and 12 a may be disposed inorder.

FIG. 5 shows a structure that a near infrared absorption layer isrespectively formed on both sides of a polymer film in the opticalfilter of FIG. 1.

An optical filter 10 d according to FIG. 5 has a structure that a pairof near infrared absorption layers 12 and 12′ is respectively disposedon both sides of the polymer film 11. The pair of near infraredabsorption layers 12 and 12′ may be formed as one layer wherein thefirst and second near infrared absorption materials are united as onebody as shown in FIG. 5, but at least one of the pair of near infraredabsorption layers 12 and 12′ may include the first and second nearinfrared absorption layers 12 a and 12 b as shown in FIGS. 2 to 4.

As shown above, even though the layer number of the near infraredabsorption layer 12 and its disposition relationship with the polymerfilm 11 are variously changed, all the optical filters 10, 10 a, 10 b,10 c, and 10 d according to some example embodiments may limit and/orminimize an optical distortion phenomenon of an image sensor.Accordingly, the optical filters 10, 10 a, 10 b, 10 c, and 10 d may bevariously disposed considering their relationship with a camera moduleand other constituent elements in an electronic device as describedabove.

The optical filter 10 may further include an anti-reflection layer onone surface of the polymer film 11 and/or on at least one surface of thenear infrared absorption layer 12.

FIG. 6 is a schematic view showing a stack structure of an opticalfilter including an anti-reflection layer according to some exampleembodiments.

Referring to FIG. 6, an optical filter 10 f further includes ananti-reflection layer 13 on the upper surface of the near infraredabsorption layer 12.

The anti-reflection layer 13 may play a role of limiting and/orpreventing reflection of an incident visible ray through the opticalfilter 10 f and improving visible light transmittance of the opticalfilter 10 and in addition, lowering visible ray reflectance and thuseffectively reducing or preventing an optical distortion by reflectedlight.

Among conventional optical filters, a method of disposing both the nearinfrared absorption layer and the near infrared ray reflection layer isused in order to block a near infrared ray. However, this optical filtermay excellently block a near infrared ray itself but rarely securevisible ray transmittance.

However, the optical filter 10 f according to some example embodimentsmay absorb light in a near infrared ray wavelength region by using thenear infrared absorption layer 12 and simultaneously, include theanti-reflection layer 13 instead of a near infrared ray reflection layerand thus have improved visible ray transmittance. Accordingly, theoptical filter 10 f according to some example embodiments has excellentnear infrared ray absorption capability and visible ray transmittancesimultaneously.

The anti-reflection layer 13 may be any layer capable of limiting and/orpreventing reflection of light in a visible ray wavelength region buttransmitting a visible ray toward the polymer film 11 without aparticular limit, for example, a multilayer including a high refractiveindex anti-reflection layer, an anti-reflection layer including a highrefractive index nano particle, or a plurality of layer having adifferent refractive indexes but is not limited thereto.

FIGS. 7 and 8 are schematic views showing various stack structures ofthe anti-reflection layer.

Referring to FIG. 7, the anti-reflection layer 13 may include a firstlayer 13 a and a second layer 13 b respectively formed of each materialhaving a different refractive index, and referring to FIG. 8, the firstand second layers 13 a and 13 b are alternately at least twice stacked.

The first and second layers 13 a and 13 b may be for example adielectric layer respectively including an oxide layer, a nitride layer,an oxynitride layer, a sulfide layer, or a combination thereof, forexample, when the second layer 13 b meets incident light first, thesecond layer 13 b has a lower refractive index than that of the firstlayer 13 a. For example, the second layer 13 b may have a refractiveindex of less than about 1.7, and the first layer 13 a may have arefractive index of greater than or equal to about 1.7.

Within the range, the second layer 13 b may for example have arefractive index ranging from greater than or equal to about 1.1 andless than about 1.7, the first layer 13 a may have a refractive indexranging from about 1.7 to about 2.7, within the range, the second layer13 b may for example have a refractive index ranging from about 1.2 toabout 1.6, and the first layer 13 a may have a refractive index rangingfrom about 1.8 to about 2.5.

The first and second layers 13 a and 13 b may be formed of any materialhaving the refractive indexes without a particular limit, for example,the first layer 13 a may be formed of titanium oxide, zinc oxide, indiumoxide, zirconium oxide, or a combination thereof, and the second layer13 b may be formed of silicon oxide, aluminum oxide, or a combinationthereof. The first and second layers 13 a and 13 b may be for exampleabout 5 to about 80 layers, and within the range, for example, about 5to about 50 layers.

The first and second layers 13 a and 13 b may have a thicknessdetermined depending on a refractive index and a reflection wavelengthof each layer, and herein, the first layer 13 a may have for example athickness of about 30 nm to about 600 nm, and the second layer 13 b mayhave a thickness ranging from about 10 nm to about 700 nm. The first andsecond layers 13 a and 13 b may have the same or different thickness.

The anti-reflection layer 13 may for example have a thickness rangingfrom about 1 μm to about 20 μm.

FIGS. 9 to 13 show various examples of disposition relationships of ananti-reflection layer in an optical filter according to some exampleembodiments.

Referring to FIG. 9, the optical filter 10 f has the anti-reflectionlayer 13 beneath the polymer film 11 unlike the one of FIG. 6. However,inventive concepts are not limited thereto and the anti-reflection layer13 may be variously disposed with a consideration to its relationshipwith other constituent elements in an electronic device.

For example, an optical filter 10 g has a pair of anti-reflection layers13 and 13′ respectively disposed on the near infrared absorption layer12 and beneath the polymer film 11 as shown in FIG. 10. On the otherhand, when an optical filter includes a pair of near infrared absorptionlayers 12 and 12′ as shown in FIG. 5, the anti-reflection layer 13 maybe respectively disposed on either one of the pair of near infraredabsorption layers 12 and 12′ (the optical filter 10 h of FIG. 11 and theoptical filter 10 i of FIG. 12) or both of them (the optical filter 10 jof FIG. 13).

In this way, the optical filters 10 e, 10 f, 10 g, 10 h, 10 i, and 10 jaccording to some example embodiments may limit and/or minimize anoptical distortion phenomenon of an image sensor, even though theanti-reflection layer 13 has various dispose structures, andaccordingly, the anti-reflection layer 13 may be variously disposed witha consideration to its relationship with a camera module and otherconstituent elements in an electronic device.

For example, the optical filter 10 may have an average lighttransmittance of less than or equal to about 25%, less than or equal toabout 20%, less than or equal to about 15%, less than or equal to about10%, less than or equal to about 5%, or less than or equal to about 4%in a wavelength region of about 700 nm to about 1200 nm.

Particularly, the optical filter 10 may have an average lighttransmittance of less than or equal to about 5% or less than or equal toabout 4% in a wavelength region of about 700 nm to about 740 nm and mayhave an average light transmittance of less than or equal to about 25%,less than or equal to about 20%, less than or equal to about 15%, lessthan or equal to about 14%, less than or equal to about 13%, less thanor equal to about 12%, less than or equal to about 11%, or less than orequal to about 10% in a wavelength region of about 1000 nm to about 1200nm.

In addition, the optical filter 10 may have an average lighttransmittance of greater than or equal to about 80%, for example greaterthan or equal to about 81%, greater than or equal to about 82%, greaterthan or equal to about 83%, greater than or equal to about 84%, greaterthan or equal to about 85%, greater than or equal to about 86%, greaterthan or equal to about 87%, or greater than or equal to about 88% in awavelength region of about 430 nm to about 565 nm.

In other words, the optical filter 10 uses the first and second nearinfrared absorption materials having different near infrared rayabsorption intensity and absorption wavelength ranges and thus showsexcellent near infrared ray absorption capability and visible ray lighttransmittance.

On the other hand, the optical filter 10 may be easily formed as a thinfilm having a thickness ranging from hundreds of micrometer to tens ofmicrometer without a particular limit. A thickness of the optical filter10 may be for example greater than or equal to about 20 μm, greater thanor equal to about 25 μm, greater than or equal to about 30 μm, greaterthan or equal to about 45 μm, greater than or equal to about 50 μm,greater than or equal to about 55 μm, greater than or equal to about 60μm, greater than or equal to about 65 μm, greater than or equal to about70 μm and may be for example less than or equal to about 210 μm, lessthan or equal to about 200 μm, less than or equal to about 190 μm, lessthan or equal to about 180 μm, less than or equal to about 170 μm, lessthan or equal to about 160 μm, less than or equal to about 150 μm, orless than or equal to about 140 μm, or may be for example about 50 μm toabout 150 μm.

An optical filter for near infrared ray absorption may have a thicknessranging from about 210 μm to about 250 μm when a glass substrate is usedbut no more be thinner due to a limit of the material. In addition, whenthe glass substrate is simply replaced with a plastic substrate in orderto solve this problem, an optical distortion phenomenon of an imagesensor may be accentuated by the aforementioned flare phenomenon.

However, the optical filter 10 according to some example embodiments maybe formed into a thin film having a thickness within the above range andsimultaneously, have excellent visible ray light transmittance and nearinfrared ray absorption capability as described above. Accordingly, theoptical filter 10 may minimize an optical distortion phenomenon of anelectronic device such as an image sensor and the like and contribute todown-sizing the electronic device.

FIG. 14 is a schematic view showing a camera module according to someexample embodiments.

Referring to FIG. 14, a camera module 20 includes a lens barrel 21, ahousing 22, an optical filter 10, and an image sensor 23.

The lens barrel 21 includes at least one lens imaging a subject, and thelens may be disposed along an optical axis direction. Herein, theoptical axis direction may be a vertical direction of the lens barrel21.

The lens barrel 21 is internally housed in the housing 22 and unitedwith the housing 22. The lens barrel 21 may be moved in optical axisdirection inside the housing 22 for autofocusing.

The housing 22 supports and houses the lens barrel 21 and may be open inthe optical axis direction. Accordingly, incident light from one surfaceof the housing 22 may reach the image sensor 21 through the lens barrel21 and the optical filter 10.

The housing 22 may be equipped with an actuator for moving the lensbarrel 21 in the optical axis direction. The actuator may include avoice coil motor (VCM) including a magnet and a coil. However, variousmethods such as a mechanical driving system or a piezoelectric drivingsystem using a piezoelectric device other than the actuator may beadopted.

The optical filter 10 is the same as described above and/or may besubstituted with any one of the optical filters 10 a, 10 b, 10 c, 10 d,10 e, 10 f, 10 g, 10 h, and/or 10 i described above.

The image sensor 23 may concentrate an image of a subject and thus storeit as data, and the stored data may be displayed as an image through adisplay media.

The image sensor 23 may be mounted in a substrate (not shown) andelectrically connected with the substrate. The substrate may be, forexample, a printed circuit board (PCB) or electrically connected to aprinted circuit board, and the printed circuit may be, for example,flexible printed circuit (FPCB).

The image sensor 23 concentrates light passing the lens barrel 21 andthe optical filter 10 and generates a video signal and may be acomplementary metal-oxide semiconductor (CMOS) image sensor and/or acharge coupled device (CCD) image sensor.

FIG. 15 is a top plan view showing an organic CMOS image sensor as anexample of an image sensor and FIG. 16 is a cross-sectional view showingan example of the organic CMOS image sensor of FIG. 15.

Referring to FIGS. 15 and 16, an organic CMOS image sensor 23A accordingto some example embodiments includes a semiconductor substrate 110integrated with photo-sensing devices 50 a and 50 b, a transmissiontransistor (not shown), and a charge storage 55, a lower insulationlayer 60, a color filter layer 70, a upper insulation layer 80, and anorganic photoelectric device 200.

The semiconductor substrate 110 may be a silicon substrate, and isintegrated with the photo-sensing devices 50 a and 50 b, thetransmission transistor (not shown), and the charge storage 55. Thephoto-sensing devices 50 a and 50 b may be photodiodes.

The photo-sensing devices 50 a and 50 b, the transmission transistor,and/or the charge storage 55 may be integrated in each pixel, and forexample as illustrated in FIG. 16, the photo-sensing devices 50 a and 50b may be included in a blue pixel and a red pixel and the charge storage55 may be included in a green pixel.

The photo-sensing devices 50 a and 50 b sense light, the informationsensed by the photo-sensing devices may be transferred by thetransmission transistor, the charge storage 55 is electrically connectedto the organic photoelectric device 100, and the information of thecharge storage 55 may be transferred by the transmission transistor.

A metal wire (not shown) and a pad (not shown) are formed on thesemiconductor substrate 110. In order to decrease signal delay, themetal wire and pad may be made of a metal having low resistivity, forexample, aluminum (Al), copper (Cu), silver (Ag), and alloys thereof,but is not limited thereto. However, it is not limited to the structure,and the metal wire and pad may be disposed under the photo-sensingdevices 50 a and 50 b.

The lower insulation layer 60 is formed on the metal wire and the pad.The lower insulation layer 60 may be made of an inorganic insulatingmaterial such as a silicon oxide and/or a silicon nitride, or a lowdielectric constant (low K) material such as SiC, SiCOH, SiCO, and SiOF.The lower insulation layer 60 has a trench exposing the charge storage55. The trench may be filled with fillers.

A color filter layer 70 is formed on the lower insulation layer 60. Thecolor filter layer 70 includes a blue filter 70 a formed in the bluepixel and a red filter 70 b formed in the red pixel. In FIG. 16, a greenfilter is not included, but a green filter may be further included.

The upper insulation layer 80 is formed on the color filter layer 70.The upper insulation layer 80 eliminates a step caused by the colorfilter layer 70 and smoothes the surface. The upper insulation layer 80and lower insulation layer 60 may include a contact hole (not shown)exposing a pad, and a through-hole 85 exposing the charge storage 55 ofa green pixel.

The organic photoelectric device 200 is formed on the upper insulationlayer 80. The organic photoelectric device 200 includes a lowerelectrode 210 and an upper electrode 220 facing each other and alight-absorbing layer 230 disposed between the lower electrode 210 andthe upper electrode 220.

The lower electrode 210 and the upper electrode 220 may be alllight-transmitting electrodes and the light-absorbing layer 230 mayselectively absorb light in a green wavelength region and may replace acolor filter of a green pixel.

As described above, the semiconductor substrate 110 and the organicphotoelectric device 200 selectively absorbing light in a greenwavelength region have a stack structure and thereby the size of animage sensor may be reduced to realize a down-sized image sensor.

Focusing lens (not shown) may be further formed on the organicphotoelectric device 200. The focusing lens may control a direction ofincident light and gather the light in one region. The focusing lens mayhave a shape of, for example, a cylinder or a hemisphere, but is notlimited thereto.

In FIGS. 15 and 16, a structure where the organic photoelectric deviceselectively absorbing light in a green wavelength region is stacked onthe semiconductor substrate 110 is illustrated, but the presentdisclosure is not limited thereto. An organic photoelectric deviceselectively absorbing light in a blue wavelength region may be stackedon the semiconductor substrate 110 and a green photo-sensing device anda red photo-sensing device may be integrated in the semiconductorsubstrate 110 or an organic photoelectric device selectively absorbinglight in a red wavelength region may be stacked on the semiconductorsubstrate 110 and a green photo-sensing device and a blue photo-sensingdevice may be integrated in the semiconductor substrate 110.

Among the light in a visible region passing the lens barrel 21 and theoptical filter 10, light in a green wavelength region may be mainlyabsorbed in the light-absorbing layer 30 and photoelectricallyconverted, and light in a blue wavelength region and a red wavelengthregion may pass the lower electrode 210 and be sensed by thephoto-sensing devices 50 a and 50 b.

As described above, the optical filters 10 and 10 a to 10 i mayeffectively transmit light in a visible region but absorb and blocklight in a near infrared region and thus transfer pure light in avisible region to an image sensor and resultantly, reduce or prevent acrosstalk generated when a signal by light in a visible region and asignal by light in a non-visible region are crossed and mixed in.

In addition, since the near infrared absorption layer is easily madeinto a thin film, the optical filter 10 and 10 a to 10 i may be easilyapplied to an electronic device such as the camera module 20, theorganic photoelectric device 200, and the like, which is down-sized.

Hereinafter, the embodiments are illustrated in more detail withreference to examples. However, these examples are non-limiting, and thepresent scope is not limited thereto.

Optical Characteristic Comparison of Polymer Films

Polymer films 1 to 5 having a thickness of about 40 μm are respectivelyprepared. A composition, a color coordinate (a*, b*) expressed as a CIELab color space, haze, a yellow index, and average light transmittancein a wavelength region of about 430 nm to about 565 nm about the polymerfilms 1 to 5 are measured, and the results are shown in Table 1.

Optical characteristics except for the composition are measured by usinga spectrophotometer (CM3600d. Minolta Co., Ltd.).

TABLE 1 Average light transmittance [%] in a wavelength region of Compo-Haze Yellow about 430 nm sition a* b* [%] index to about 565 nm Polymerfilm 1 TAC −0.1 0.4 0.2 2.0 92.0 Polymer film 2 COP −0.1 0.2 0.2 1.791.0 Polymer film 3 PET −0.1 0.8 1.2 3.0 87.8 Polymer film 4 PC −0.1 0.50.4 2.3 88.4 Polymer film 5 PI −0.98 2.3 0.9 2.8 85.0

Referring to Table 1, the polymer films 1 to 5 all satisfy the abovecolor coordinate, haze, yellow index, and average light transmittance ina wavelength region of about 430 nm to about 565 nm within predeterminedranges. Accordingly, the polymer films 1 to 5 all may be used as thepolymer film 11 of the optical filter 10 according to some exampleembodiments.

Coating Property Comparison of Copper Compound for First Near InfraredAbsorption Layer

Each copper compound composition 1 to 12 is prepared by mixing a coppercompound and a solvent. Subsequently, each copper compound composition 1to 12 is respectively tried to use to form a first near infraredabsorption layer, and then, each composition of the copper compound, adissolution degree of the copper compound, and its precipitation or notafter the coating are shown in Table 2.

TABLE 2 Precipitation Composition Solvent Solubility after coatingCopper compound Chemical tetrahydrofuran ⊚ precipitation X composition 1Formula 4a Copper compound Chemical acetone ⊚ precipitation Xcomposition 2 Formula 4a Copper compound Chemical methylisobutyl ⊚precipitation X composition 3 Formula 4a ketone Copper compound coppertetrahydrofuran ⊚ precipitation ◯ composition 4 compound a Coppercompound copper acetone X precipitation ◯ composition 5 compound aCopper compound copper methylisobutyl X precipitation ◯ composition 6compound a ketone Copper compound copper tetrahydrofuran X coating Xcomposition 7 compound b Copper compound copper acetone X coating Xcomposition 8 compound b Copper compound copper methylisobutyl X coatingX composition 9 compound b ketone Copper compound copper tetrahydrofuranX coating X composition 10 compound c Copper compound copper acetone Xcoating X composition 11 compound c Copper compound coppermethylisobutyl X coating X composition 12 compound c ketone

In Table 2, the copper compounds a to c are respectively as follows.

[Copper compound c]

Copper (II) Sulfate

Referring to Table 2, a copper phosphate ester compound represented byChemical Formula 4a as a copper compound shows excellent solubilityabout all three kinds of solvents (tetrahydrofuran, acetone, ormethylisobutylketone) and is not precipitated after the coating and thussecures excellent stability of a coating layer.

The copper compound a as a copper compound shows insufficient solubilityabout the other solvents except for tetrahydrofuran and is precipitatedafter the coating and thus shows instability of a coating layer.

On the other hand, both the copper compounds b and c shows insufficientsolubility about three kinds of solvents and thus may not form a coatinglayer.

Accordingly, referring to Table 2, the copper phosphate ester compoundrepresented by Chemical Formula 4a turns out to be an appropriate coppercompound for a composition for a first near infrared absorption layer.

Optical Characteristic Comparison of Organic Dyes for Forming SecondNear Infrared Absorption Layer

Solutions are prepared by respectively dissolving organic dyes 1-6, inchloroform 0.5×10⁻³ wt % are prepared. Subsequently, a composition, amaximum absorption wavelength (λ_(max)), average light transmittance ata maximum absorption wavelength (λ_(max)), average light transmittanceat a wavelength of 550 nm, and a ratio (abs_(λmax)/abs_(550nm)) ofabsorbance at a maximum absorption wavelength relative to absorbance ata wavelength of 550 nm about the organic dyes 1 to 6 in each of theprepared solutions are respectively shown in Table 3.

Optical characteristics except for the composition are measured by usinga UV-Vis spectrophotometer (SoldiSpec-3700, Shimadzu Corp.).

TABLE 3 Average Average light trans- light trans- Composi- λ_(max)mittance mittance abs_(λmax)/ tion [nm] @λ_(max) [%] @550 nm [%]abs_(550 nm) Organic Chemical 747 96.2 4.1 82:1 dye 1 Formula 1a OrganicChemical 760 95.7 12.9 47:1 dye 2 Formula 1b Organic Chemical 725 96.810.6 64:1 dye 3 Formula 1c Organic Chemical 1075 98.1 32.5 57:1 dye 4Formula 2a Organic Chemical 1070 97.1 57.9 19:1 dye 5 Formula 2b OrganicChemical 1084 98.9 62.7 44:1 dye 6 Formula 2c

Referring to Table 3 regarding the organic dyes 1 to 3 belonging toChemical Formula 1, the organic dye 1 having an anion of PF₆ ⁻ showsvery excellent abs_(λmax)/abs_(660nm) compared with those of the organicdyes 2 and 3 having an anion of I⁻, but when the same anion (L) is used,the organic dye 3 in which R¹ and R² in Chemical Formula 1 are alkylgroups having more carbons shows excellent absλmax /abs550 nm comparedwith the organic dye 2 in which R¹ and R² in Chemical Formula 1 arealkyl groups having less carbons.

On the other hand, regarding the organic dyes 4 to 6 belonging toChemical Formula 2, the organic dye 4 having an anion of PF₆ ⁻ and theorganic dye 6 having a borate-based ion as an anion show very excellentabs_(λmax)/abs_(550nm) compared with the organic dye 5 having an anionof ClO₄ ⁻.

Manufacture of Optical Filter

Example 1

A first near infrared absorption layer is formed by coating a copperphosphate salt composition prepared by mixing a THF solvent and copperphosphate ester represented by Chemical Formula 4a on a polymer film, aTAC film (Fuji Tekko Co., Ltd.) and drying it.

Subsequently, on the first near infrared absorption layer, a second nearinfrared absorption layer is formed by coating a composition for asecond near infrared absorption layer which is prepared by mixing anorganic dye represented by Chemical Formula 1a, an organic dyerepresented by Chemical Formula 2a, an acryl-based binder, andmethylethylketone as an organic solvent and then, drying it.

On the second near infrared absorption layer, an anti-reflection coatinglayer (ARC-100, Don Co., Ltd.) is formed to manufacture an opticalfilter according to Example 1 (polymer film/first near infraredabsorption layer/second near infrared absorption layer/anti-reflectionlayer). The optical filter has a thickness of about 120 μm.

Example 2

An optical filter according to Example 2 (anti-reflection layer/polymerfilm/first near infrared absorption layer/second near infraredabsorption layer/anti-reflection layer) is manufactured according to thesame method as Example 1 except for using a polymer film having ananti-reflection layer on the lower surface (DSG-17 TG60, Dai NipponPrinting Co., Ltd.). The optical filter has a thickness of about 117 μm.

Example 3

An optical filter according to Example 3 (anti-reflection layer/polymerfilm/first near infrared absorption layer/second near infraredabsorption layer/anti-reflection layer) is manufactured according to thesame method as Example 1 except for using a polymer film having ananti-reflection layer on the lower surface (DSG-17 TG60, Dai NipponPrinting Co., Ltd.) and further including an organic dye represented byChemical Formula 3 in the composition for a second near infraredabsorption layer. The optical filter has a thickness of about 117 μm.

Example 4

An optical filter according to Example 4 (polymer film/first nearinfrared absorption layer/second near infrared absorption layer) ismanufactured according to the same method as Example 1 except foromitting the anti-reflection layer. The optical filter has a thicknessof about 115 μm.

Comparative Example 1

An optical filter according to Comparative Example 1 (polymer film/firstnear infrared absorption layer) is manufactured according to the samemethod as Example 1 except for omitting the second near infraredabsorption layer and the anti-reflection layer. The optical filter has athickness of about 110 μm.

Comparative Example 2

An optical filter according to Comparative Example 2 (polymerfilm/second near infrared absorption layer) is manufactured according tothe same method as Example 1 except for forming the second near infraredabsorption layer on the polymer film without forming the first nearinfrared absorption layer and omitting the anti-reflection layer. Theoptical filter has about thickness of 110 μm.

Light Transmittance of Optical Filters of Examples and ComparativeExamples Depending on Wavelength

Light transmittance characteristics of the optical filters according toExamples and Comparative Examples depending on a wavelength region areevaluated, and the results are shown in FIG. 17.

The light transmittance characteristics are evaluated by using a UV-Visspectrophotometer (SoldiSpec-3700, Shimadzu Corp.).

FIG. 17 is a graph showing light transmittances of the optical filtersaccording to Examples and Comparative Examples depending on awavelength.

Referring to FIG. 17, the optical films according to Examples showexcellent average light transmittance in a wavelength region rangingfrom 430 nm to 565 nm and simultaneously, excellent average lighttransmittance in a wavelength region of 700 nm to 740 nm, 700 nm to 1200nm, and 1000 nm to 1200 nm compared with the optical films according toComparative Examples.

The optical films including at least one anti-reflection layer show alittle improved average light transmittance (about 5% to 7%) in awavelength region ranging from 430 nm to 565 nm compared with theoptical films not including at least one anti-reflection layer.

On the other hand, Table 4 shows average light transmittances of theoptical films according to Examples and Comparative Examples in eachwavelength region (430 nm to 565 nm, 700 nm to 740 nm, 700 nm to 1200nm, and 1000 nm to 1200 nm) in FIG. 17.

TABLE 4 430 nm- 700 nm- 700 nm- 1000 nm- 565 nm [%] 740 nm [%] 1200 nm[%] 1200 nm [%] Example 1 86.0 4.8 5.8 10.0 Example 2 88.4 4.8 5.7 9.8Example 3 88.0 3.1 5.6 9.9 Example 4 82.7 4.8 5.8 10.1 Comparative 89.233.3 34.7 47.3 Example 1 Comparative 82.9 1.1 35.8 27.8 Example 2

Referring to Table 4, the optical films according to ComparativeExamples 1 and 2 show excellent average light transmittance in awavelength region of about 430 nm to about 565 nm but average lighttransmittance of 27% to 50% in at least one section out of the othernear infrared ray wavelength regions (700 nm to 740 nm, 700 nm to 1200nm, and 1000 nm to 1200 nm).

Accordingly, referring to Table 4, the optical filters according toExamples show excellent light transmittance in visible ray wavelengthregion and excellent light absorption capability in near infrared raywavelength region compared with the optical films according toComparative Examples.

While some example embodiments have been described, it is to beunderstood that inventive concepts not limited to the disclosedembodiments, but, on the contrary, are intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An optical filter, comprising a polymer film having a* of about −5.0 to about +5.0 and b* of about −5.0 to about +5.0, based on a color coordinate expressed by a CIE Lab color space; and a near infrared absorption layer on the polymer film, the near infrared absorption layer being configured to transmit light in a visible region and to selectively absorb at least one part of light in a near infrared region, the near infrared absorption layer including a first near infrared absorption material and a second near infrared absorption material, the first near infrared absorption material including a copper phosphate ester compound, the second near infrared absorption material including at least two different organic dyes, and the second near infrared absorption material having a maximum absorption wavelength (λ_(max)) in a wavelength region of about 650 nm to about 1200 nm, wherein the second near infrared absorption material includes a binder, the at least two different organic dyes of the second near infrared absorption material include an organic dye represented by Chemical Formula 1 and at least one of an organic dye represented by Chemical Formula 2 or an organic dye represented by Chemical Formula 3,

wherein, in Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3, R¹ to R²⁶ are independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group, X is one of PF₆ ⁻, BF₄ ⁻, ClO₄ ⁻, I⁻, or a borate-based anion, and n is an integer ranging from 1 to
 10. 2. The optical filter of claim 1, wherein the organic dye represented by Chemical Formula 1 includes one or more structures represented by at least one of Chemical Formula 1a, Chemical Formula 1b, Chemical Formula 1c, Chemical Formula 1d, or Chemical Formula 1e:


3. The optical filter of claim 1, wherein the organic dye represented by Chemical Formula 2 includes one or more structures represented by at least one of Chemical Formula 2a, Chemical Formula 2b, or Chemical Formula 2c:


4. The optical filter of claim 1, wherein the organic dye represented by Chemical Formula 1 has a maximum absorption wavelength (λ_(max)) in a wavelength region of about 700 nm to about 760 nm, the organic dye represented by Chemical Formula 2 has a maximum absorption wavelength (λ_(max)) in a wavelength region of about 1050 nm to about 1100 nm, and the organic dye represented by Chemical Formula 3 has a maximum absorption wavelength (λ_(max)) in a wavelength region of about 680 nm to about 720 nm.
 5. The optical filter of claim 1, wherein the binder includes an acrylic binder, an epoxy binder, or a combination thereof.
 6. The optical filter of claim 1, wherein the organic dye represented by Chemical Formula 1 has an absorbance at a maximum absorption wavelength (λ_(max)) that is at least about 30 times as high as an absorbance of the organic dye represented by Chemical Formula 1 at a wavelength of about 550 nm, and the organic dye represented by Chemical Formula 2 has an absorbance at a maximum absorption wavelength (λ_(max)) that is at least about 15 times as high as an absorbance of the organic dye represented by Chemical Formula 2 at a wavelength of about 550 nm.
 7. The optical filter of claim 1, wherein the copper phosphate ester compound is represented by Chemical Formula 4:

wherein, in Chemical Formula 4, R⁴¹ and R⁴² are independently one of a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, or a substituted or unsubstituted C6 to C20 aryl group, n₁ is an integer of 0 or 1, and n₂ is an integer of 1 or
 2. 8. The optical filter of claim 7, wherein the copper phosphate ester compound represented by Chemical Formula 4 includes one or more structures represented by at least one of Chemical Formula 4a, Chemical Formula 4b, Chemical Formula 4c, or Chemical Formula 4d:


9. The optical filter of claim 1, wherein the near infrared absorption layer includes a first near infrared absorption layer and a second near infrared absorption layer, the first near infrared absorption layer consisting of the first near infrared absorption material, the second near infrared absorption layer consisting of the second near infrared absorption material, and the first near infrared absorption layer and the second near infrared absorption layer are separate layers from each other.
 10. The optical filter of claim 9, wherein the first near infrared absorption layer is on the polymer film and the second near infrared absorption layer is on the first near infrared absorption layer.
 11. The optical filter of claim 1, wherein the optical filter further includes an anti-reflection layer on at least one of one surface of the polymer film or one surface of the near infrared absorption layer.
 12. The optical filter of claim 11, wherein the anti-reflection layer includes a first layer and a second layer, a refractive index of the first layer is different than a refractive index of the second layer, and the first layer and the second layer are alternately stacked two or more.
 13. The optical filter of claim 11, wherein the optical filter includes an anti-reflection layer on the one surface of the polymer film and the one surface of the near infrared absorption layer, respectively.
 14. The optical filter of claim 1, wherein the polymer film includes one of polyethyleneterephthalate, polyethylenenaphthalate, triacetyl cellulose, polycarbonate, a cycloolefin polymer, poly(meth)acrylate, polyimide, or a combination thereof.
 15. The optical filter of claim 1, wherein a yellow index of the polymer film measured according to ASTM D1925 is less than or equal to about
 10. 16. The optical filter of claim 1, wherein a haze of the polymer film is less than or equal to about 10%.
 17. The optical filter of claim 1, wherein the optical filter has a thickness of about 25 μm to about 190 μm.
 18. The optical filter of claim 17, wherein the optical filter has an average light transmittance of less than or equal to about 25% in a wavelength region of about 700 nm to about 1200 nm.
 19. The optical filter of claim 17, wherein the optical filter has an average light transmittance of less than or equal to about 5% in a wavelength region of about 700 nm to about 740 nm, and the optical filter has an average light transmittance of less than or equal to about 25% in a wavelength region of about 1000 nm to about 1200 nm.
 20. The optical filter of claim 17, wherein the optical filter has an average light transmittance of greater than or equal to about 80% in a wavelength region of about 430 nm to about 565 nm.
 21. A camera module comprising a lens; an image sensor; and the optical filter of claim 1 between the lens and the image sensor.
 22. An electronic device comprising: a substrate; a photo-sensing device integrated with the substrate; and the optical filter of claim 1 on the photo-sensing device.
 23. An optical filter, comprising a polymer film having a* of about −5.0 to about +5.0 and b* of about −5.0 to about +5.0, based on a color coordinate expressed by a CIE Lab color space; and a near infrared absorption layer on the polymer film, the near infrared absorption layer including a first near infrared absorption layer and a second near infrared absorption layer, the first near infrared absorption layer including a copper phosphate ester compound represented by Chemical Formula 4,

 and the second near infrared absorption layer including a binder and a plurality of organic dyes having a maximum absorption wavelength (λ_(max)) in a wavelength region of about 650 nm to about 1200 nm, wherein, in Chemical Formula 4, R⁴¹ and R⁴² are independently one of a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, or a substituted or unsubstituted C6 to C20 aryl group, n₁ is an integer of 0 or 1, and n₂ is an integer of 1 or 2 wherein the plurality of organic dyes include an organic dye represented by Chemical Formula 1 and at least one of an organic dye represented by Chemical Formula 2 or an organic dye represented by Chemical Formula 3,

wherein, in Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3, R¹ to R²⁶ are independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group, X is one of PF₆ ⁻, BF₄ ⁻, ClO₄ ⁻, I⁻, or a borate-based anion, and n is an integer ranging from 1 to
 10. 24. The optical filter of claim 23, wherein the copper phosphate ester compound represented by Chemical Formula 4 includes one or more structures represented by at least one of Chemical Formula 4a, Chemical Formula 4b, Chemical Formula 4c, or Chemical Formula 4d,

the plurality of organic dyes include a first organic dye represented by Chemical Formula 1 and at least one of a second organic dye represented by Chemical Formula 2 or a third organic dye represented by Chemical Formula 3,

wherein, in Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3, R¹ to R²⁶ are independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group, X is one of PF₆ ⁻, BF₄ ⁻, ClO₄ ⁻, I⁻, or a borate-based anion, and n is an integer ranging from 1 to
 10. 25. The optical filter of claim 23, further comprising at least one of: a binder in the second near infrared absorption layer, or an anti-reflection layer on the polymer film.
 26. An electronic device comprising: a photoelectric device; and the optical filter of claim 23 on the photoelectric device.
 27. An electronic device comprising: a substrate; a photo-sensing device integrated with the substrate; and the optical filter of claim 23 on the photo-sensing device. 